Mean-Life Measurements of Excited Electronic States in Neutral and Ionic Species of Beryllium and Boron

Abstract

Lifetimes of excited states in neutral and ionic species of beryllium and boron have been measured by using the foil-excitation technique. Ion beams from 60 to 400 keV produced with an electromagnetic isotope separator or a heavy-ion accelerator were used. The 1600-7000 \AA{} wavelength region was investigated. For low-lying states in Be, the beam-foil excitation mechanism was studied. Mean lives of 11 states in Be I, nine in Be II, and one in Be III have been measured. Three lines belonging to beryllium could not be identified. In the boron case, seven mean lives were determined for excited neutral and ionic states. Transition probabilities and oscillator strengths have been evaluated and compared with theoretical predictions.